The present invention relates to a rectangular transducer for a panel-form loudspeaker, and more particularly to a rectangular transducer for exciting a flat panel of a panel-form loudspeaker to generate flexural vibration.
A conventional loudspeaker utilizes a round-shaped electromagnetic transducer to drive a cone-type membrance to radiate sound. In general, an additional enclosure is necessary to facilitate sound radiation, which makes the loudspeaker cumbersome, weighty and having dead corner for sound radiation, etc. Recently, flat display and mobile communication devices such as notebook, cellular phone and personal digital assistant (PDA), are rapidly developed toward miniaturization. The integration of transparent panel-form loudspeakers with the flat display and mobile communication devices can greatly enhance the performance of such devices. Therefore, the conventional loudspeaker is gradually replaced by a panel-form loudspeaker.
FIGS. 1(a) and 1(b) are respectively perspective and cross-sectional views of a round-shaped transducer applied in a traditional panel-form loudspeaker. The round-shaped transducer 10 includes a round permanent magnet 11, a cup-shaped permeance unit 12, a cylindrical voice coil unit 13 and a suspension unit 14. The voice coil unit 13 has a top ring 15 to be attached onto a flat panel (not shown) of a panel-form loudspeaker. The voice coil unit 13 has a moving coil 131 supported by the suspension unit 14 and immersed within the magnetic field between the magnet 11 and the permeance unit 12. When electric current flow through the moving coil 131, the voice coil unit 13 will be forced to move back and forth vertically, thereby driving the flat panel to radiate sound.
The customarily used panels for panel-form loudspeaker include both transparent and opaque panels. When the round-transducer 10 is mounted on the peripheral edge of the transparent panel, the size of the transparent panel is reduced due to the relatively large cross-sectional area of the round-transducer 10. In addition, the attached area between the top ring 15 and the panel is also too large to be treated as a point-excitation and generate the best flexural vibration for sound radiation all of the forementioned shortcomings of the round transducer 10 are adverse for the integration of the panel-form loudspeaker with the flat display and mobile communication devices.
Therefore, the present invention provides an improved structure of transducer so as to overcome the problems described above.
It is an object of the present invention to provide a structure of a transducer in a rectangular and blade-like shape, which is suitable to be mounted on peripheral edges of a transparent panel for a panel-form loudspeaker.
It is another object of the present invention to provide a structure of a rectangular transducer having a slab attached onto a panel of a panel-form loudspeaker, wherein the length and width of the slab can be optionally predetermined so as to excite good flexural vibration.
In accordance with an aspect of the present invention, there is provided a structure of a rectangular transducer. The structure includes a magnet assembly, a voice coil assembly and a positioning assembly. The magnet assembly has a pair of magnetic units with a gap therebetween for generating two magnetic fields having magnetic fluxes in opposite direction within the gap. The voice coil assembly includes a slab, a coil and a suspension unit, wherein the slab is used for being attached to a panel and the coil is immersed within the gap. The positioning assembly is used for supporting and positioning the magnet assembly and the voice coil assembly. When electric current flows through the coil, the voice coil assembly generates a motion in a direction vertical to the magnetic fluxes so as to excite the panel to generate flexural vibration and radiate sound.
Preferably, the suspension unit includes a suspending plate having a hollow region in the center and suspending arms on the right side and left side.
Preferably, the number of the suspending arms on each of the right side and left side is 2.
Preferably, the suspending plate and the suspending arms are integrally formed.
Preferably, the coil is disposed within the hollow region. In addition, the coil is a conducting line with a plurality of winding and patterned on a printed circuit board.
Preferably, the slab and the suspension unit are integrally formed.
Preferably, the positioning assembly includes a base with a channel in the center thereof and two posts.
Preferably, the two posts are respectively mounted on both ends of the channel.
Preferably, the suspending arms are in contact with the posts on the top surfaces and bottom surfaces thereof.
Preferably, the width of each of the posts is substantially equal to the distance of the gap in the magnet assembly.
Preferably, each of the posts further includes two transverse bars on both sides for facilitating the positioning of the magnet assembly.
Preferably, the pair of magnetic units are in parallel alignment with opposite polar disposition.
Preferably, each of the magnetic units includes a magnet having poles on both vertical edge sides and sandwiched by two face pole plates.
Preferably, each of the magnetic units includes a U-shaped magnet having poles on both end sides.
Preferably, each of the magnetic units includes a free-permeable sheet sandwiched by two magnets, wherein each of the two magnets has poles on both horizontal edge sides and the two magnet are aligned with opposite polar disposition. In addition, each of the magnetic units further includes a face pole plate attached to with the free-permeable sheet and the two magnets exteriorly.
Preferably, the gap is in a range between 0.5 and 5 mm.
Preferably, the slab and the suspending unit of the voice coil assembly are made of a material selected from a group consisting of plastic and aluminum.
Preferably, the positioning assembly is made of a material selected from a group consisting of plastic and aluminum.
In accordance with another aspect of the present invention, there is provided a rectangular transducer. The rectangular transducer includes a magnet assembly having a pair of magnetic units with a gap therebetween for generating a first magnetic field and a lower magnetic field having magnetic fluxes in opposite direction within the gap, a voice coil assembly comprising a slab, a coil and a suspension unit, wherein the slab is used for being attached to a panel and the coil is immersed within the gap, and a positioning assembly for supporting and positioning the magnet assembly and the voice coil assembly, wherein the positioning assembly, the slab and the suspending unit are integrally formed, and when electric current flows through the coil, the voice coil assembly generates a motion in a direction vertical to the magnetic fluxes so as to excite the panel to generate flexural vibration and radiate sound.
Preferably, the positioning assembly, the slab and the suspending unit are made of a plastic material.
The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: